Handheld computer devices are to be carried by hundreds of officers on the beat so they can access national police databases in seconds.

The PDAs, which boast a camera, screen and telephone, are to be used in Oxford after street trials by 70 Thames Valley Police officers since March.

The new six-month trial, to be launched next spring, will bring the number of users in the force up to 350.

The devices can be used for rapid identity and vehicle checks.

Officers can also read their emails while out on patrol.

Keith Gough, project leader for the force, said: "The device enables officers to get away from their desks, away from the computers upon which we are so reliant, and to spend more time out on the streets providing a visible policing presence."

If the Oxford trial is successful, the devices could be used by officers across the force.